JP5194867B2 - In-vehicle device for smart entry system - Google Patents

Description

  The present invention relates to an in-vehicle device for a smart entry system that implements various vehicle controls by communicating with a portable device carried by a user.

  Conventionally, in an automobile, a transmission request signal is transmitted from the in-vehicle device to the surroundings, and a return signal from the portable device that has received the transmission request signal is received by the in-vehicle device. The ID code as the identification information included in the returned signal is compared with the ID code registered in advance in the control device, and if the two ID codes match, the authentication is successful. Smart entry systems are known that perform vehicle control such as door unlocking (unlocking) or unlocking permission or engine start permission by driving an actuator (see, for example, Patent Documents 1 and 2).

  According to such a smart entry system, vehicle control such as unlocking the door is performed without the user performing a special key operation, so that convenience can be improved. On the other hand, it is necessary for the in-vehicle device to be periodically activated for authentication, which causes a problem that power consumption increases.

Therefore, the following configuration has been conventionally considered in this type of in-vehicle device for a smart entry system.
Specifically, the in-vehicle device includes a microcomputer (corresponding to the control device described above) that shifts to the sleep mode, and a communication IC that communicates with the portable device instead of the microcomputer when the microcomputer shifts to the sleep mode. It is a configuration (see FIG. 7).

  FIG. 7A is a configuration diagram of an electronic control device (hereinafter referred to as an ECU) 100 as such an in-vehicle device, and FIG. 7B is a time chart for explaining the operation of the ECU 100.

  In FIG. 7, while the microcomputer 110 is activated (wake mode), a transmission request signal is transmitted to the surroundings via the transmission antenna 140 under the control of the microcomputer 110. A return signal from a portable device (not shown) that has received the transmission request signal is received by the receiving antenna 130 and input to the microcomputer 110 via the communication IC 120. As described above, the microcomputer 110 compares and determines whether the ID code as the identification information included in the return signal matches the ID code registered in the microcomputer 110 in advance (FIG. 7B). : Authentication by microcomputer control).

  On the other hand, when the microcomputer 110 determines that the sleep mode may be shifted, the microcomputer 110 shifts to the sleep mode. When the microcomputer 110 is in the sleep mode, the communication IC 120 is periodically driven to transmit a transmission request signal to the surroundings via the transmission antenna 140 on behalf of the microcomputer 110 and to receive the transmission request signal. A return signal from the machine is received via the receiving antenna 130. The communication IC 120 performs simple authentication as to whether or not the return signal has been received (FIG. 7B: authentication by PWM), and outputs information represented by the received return signal to the microcomputer 110. The microcomputer 110 is activated when information indicated by the return signal is input, and performs authentication as described above.

  The driving timing of the communication IC 120 is controlled by the microcomputer 110. Specifically, the microcomputer 110 has a PWM (Pulse Width Modulation) function that outputs a pulse with a predetermined duty ratio even when the microcomputer 110 is in the sleep mode, and outputs a pulse to the communication IC 120 using this PWM function. The communication IC 120 is driven for a predetermined period at a pulse rising timing.

Here, in the ECU 100 of this example, the microcomputer 110 sets the duty ratio of the pulse to the communication IC 120 to 0 during the operation of the microcomputer 110 so that the pulse is not output to the communication IC 120 as a result. Yes. On the other hand, when the microcomputer 110 determines that the sleep mode may be entered (FIG. 7 (b): switching condition is established), the duty ratio is set to a predetermined value (FIG. 7 (b): switching request) and set. Is completed (FIG. 7B: switching completed), the mode shifts to the sleep mode. It should be noted that the setting is completed when a pulse is normally output from the microcomputer 110 to the communication circuit 120 (FIG. 7B: switching completed).
JP 2000-104429 A JP 2003-157383 A

  Incidentally, in the example as shown in FIG. 7, when the duty ratio is set (switched) in the microcomputer 110, the set value is reflected for the first time in the next cycle (see FIG. 7B).

  Further, the microcomputer 110 does not operate until the duty ratio setting (switching) is completed (that is, until a pulse is normally output from the microcomputer 110 to the communication circuit 120) before shifting to the sleep mode. There is a restriction that it must not be (wake mode). For example, the purpose is to ensure the driving reliability of the communication IC 120.

  Therefore, after setting the duty ratio, the microcomputer 110 needs to operate (wake) until the next cycle in which the set value is reflected. Specifically, in FIG. 7B, the microcomputer 110 needs to operate (wake) from the switching request timing to the switching completion timing. For this reason, power consumption will increase.

  The present invention has been made in view of these points, and aims to further reduce power consumption in an in-vehicle device for a smart entry system that performs various vehicle controls by communicating with a portable device carried by a user. To do.

The in-vehicle device for a smart entry system according to claim 1 made to achieve the above object comprises a microcomputer and a communication circuit.
The microcomputer is included in the transmission means for transmitting the transmission request signal to the surroundings, the reception means for receiving the return signal transmitted in response to the transmission request signal from the portable device possessed by the user, and the received return signal. Authentication means for performing authentication by determining whether or not the identification information being registered is identification information registered in advance, and a control means for performing specific vehicle control when authentication by the authentication means is successful Yes. The operation is stopped when a predetermined operation stop condition is satisfied.

  The communication circuit is driven for a specified period at the rising or falling timing of the input signal while the operation of the microcomputer is stopped. Instead of the microcomputer, the communication circuit receives the return signal and receives the return signal. Is output to the microcomputer.

  The microcomputer further has a pulse output circuit that outputs a pulse to the communication circuit. When the operation stop condition is satisfied, the microcomputer sets the pulse duty ratio before stopping its operation, After the output and the normal operation of the pulse output circuit can be confirmed, the self operation is stopped.

  In such an in-vehicle device for smart entry system, when the operation stop condition is satisfied, the microcomputer temporarily stops its own operation until immediately before the next cycle of the pulse (hereinafter referred to as the next cycle). It starts immediately before setting the duty ratio and confirms the operation of the pulse output circuit in the next cycle.

  By the way, in this in-vehicle device for smart entry system, the following is assumed. Specifically, when the duty ratio of the pulse is set, the duty ratio is reflected (that is, the pulse having the set duty ratio is output) in the next cycle of the pulse. For example, when the period is T and a time series such as 0 to T to 2T to 3T is considered, and the duty ratio is set to 0.5 between T and 2T, for example, the set value Is reflected (a pulse with a duty ratio of 0.5 is output) is the transition of 2T to 3T, which is the next cycle.

  Under such a premise, in the smart entry system vehicle-mounted device according to claim 1, when the microcomputer stops its operation, it does not wait for the next cycle after the duty ratio is set and the operation continues. During the next cycle, the self operation is temporarily stopped. Then, the duty ratio is set by starting immediately before the next cycle. Therefore, the power consumption of the microcomputer can be reduced by temporarily stopping the operation of the microcomputer while the set value is reflected in the next cycle. That is, while maintaining the performance of the smart entry system vehicle-mounted device, the power consumption of the smart entry system vehicle-mounted device can be further reduced.

  Next, in the smart entry system vehicle-mounted device according to claim 2, in the smart entry system vehicle-mounted device according to claim 1, in addition to the fact that the operation stop condition is satisfied, the microcomputer Since it is determined that the operation can be stopped, the self operation is temporarily stopped until immediately before the next cycle.

According to this, the operation of the microcomputer does not stop while authentication (authentication with the portable device) is being executed in the microcomputer. That is, authentication is performed reliably.
Next, the in-vehicle device for smart entry system according to claim 3 is the in-vehicle device for smart entry system according to claim 1 or 2, wherein the microcomputer is configured such that when the operation stop condition is satisfied, the interval until the next cycle is longer than a predetermined time. If it is short, the operation of the pulse output circuit is not stopped until the next period, but the duty ratio is set by the arrival of the next period and the operation of the pulse output circuit is confirmed in the next period. It has become.

  According to this, if the operation stop condition is satisfied and the interval until the next cycle is short, and the operation of the microcomputer is temporarily stopped, the start of the microcomputer is not in time by the next cycle, and the setting of the duty ratio is delayed (and eventually If there is a possibility that the output of the pulse is delayed), the microcomputer can be prevented from stopping the operation until the next cycle. Since the microcomputer sets the duty ratio before the next cycle comes, the pulse is output more reliably at a desired timing.

The apparatus of claim 3 is preferably constructed as in claim 4.
The smart entry system vehicle-mounted device according to claim 4 is the smart entry system vehicle-mounted device according to claim 3, wherein the predetermined time includes at least a time required for starting the microcomputer and a time required for setting the duty ratio ( Hereinafter, the operation is described as the operation resumption time.

  Specifically, the microcomputer continues to operate and sets the duty ratio if the interval from the establishment of the operation stop condition to the next cycle is shorter than the operation resumption time. According to this, as described in the third aspect, the pulse is output more reliably at a desired timing. On the other hand, if the interval between the operation stop condition and the next cycle is longer than the operation resumption time, the microcomputer temporarily stops its own operation. According to this, as described in claim 1, power consumption is reduced.

Next, the apparatus according to claims 3 and 4 can be configured as in claim 5.
The smart entry system vehicle-mounted device according to claim 5 is the smart entry system vehicle-mounted device according to claim 3 or 4, wherein the microcomputer includes a counter that measures a period representing a cycle, and the operation is stopped based on the count value of the counter. The interval from when the condition is satisfied to the next cycle is recognized.

  According to such a configuration, the microcomputer can easily recognize the interval from when the operation stop condition is satisfied until the next cycle, and immediately before the next cycle when the operation stop condition is satisfied. It is possible to easily determine whether to stop the operation once or until the next cycle.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a vehicle electronic control device (hereinafter referred to as ECU) 1 to which the present invention is applied.

  This ECU 1 communicates with a smart portable device (not shown) carried by the driver of the vehicle, and when authentication by communication is successful, unlocking or unlocking of the vehicle door, permission of engine start, etc. Carry out vehicle control.

  As shown in FIG. 1, the ECU 1 outputs a microcomputer 10 that executes various processes, a communication IC 40 for communicating with a smart portable device (not shown), and a power supply voltage (for example, 5 V) for operating the microcomputer 10. And a power supply IC 30.

The battery voltage VB is supplied to the power supply IC 30, and the power supply IC 30 steps down the battery voltage VB (for example, 5 V) and outputs it to the microcomputer 10.
The microcomputer 10 includes a well-known CPU 12 that operates according to a program, a ROM 14 that stores a program executed by the CPU 12 and data referred to when the program is executed, a RAM 16 that stores a calculation result of the CPU 12, and a predetermined duty. A PWM circuit 20 that outputs a ratio pulse to the communication IC 40 to control driving of the communication IC 40, a timer circuit 22, an input / output port 24, a sub oscillation circuit 26, and a main oscillation circuit 28 are provided. Are connected to each other via a bus. The PWM circuit 20 has a built-in counter (not shown) that counts a period representing the period of pulses output from the PWM circuit 20. For example, if the pulse period is T, the counter counts a period from 0 to T.

  The microcomputer 10 is activated, for example, when a vehicle ignition switch (hereinafter referred to as IGSW) 2 is turned on, and operates according to a main clock from the main oscillation circuit 28. On the other hand, when a predetermined operation stop condition is satisfied and it is determined that the mode should be shifted to the sleep mode for reducing the power consumption, the operation of the main oscillation circuit 28 is stopped and the operation is performed according to the sub clock from the sub oscillation circuit 26. . That is, it shifts to the sleep mode.

In the following description, it is assumed that the switching condition is satisfied when a predetermined operation stop condition is satisfied and authentication with the smart portable device is completed in the microcomputer 10.
In the microcomputer 10, the timer value of the timer circuit 22 is set to a predetermined value immediately before stopping its own operation. When the time represented by the set timer value comes, the timer circuit 22 outputs an activation signal for activating the microcomputer 10. As a result, the main oscillation circuit 28 operates and the operation clock of the microcomputer 10 is switched to the main clock from the main oscillation circuit 28. That is, the microcomputer 10 is activated.

  The communication IC 40 is connected to a reception antenna 50 and a transmission antenna 60 outside the ECU 1 and is configured to be able to communicate with a smart portable device (not shown). Specifically, the microcomputer 10 is driven according to a pulse from the PWM circuit 20 of the microcomputer 10 and transmits a transmission request signal for the smart portable device to the surroundings via the transmission antenna 60. Here, the communication IC 40 transmits the above-described transmission request signal to the surroundings via the transmission antenna 60 at the timing when the output level of the pulse input from the PWM circuit 20 rises to the high level as the active level.

  When the response signal from the smart portable device that has received the transmission request signal is received via the receiving antenna 50, the communication IC 40 outputs the received signal to the microcomputer 10 and outputs the authentication start signal Q. The level is set to a high level for a predetermined period.

  Next, FIG. 2 is a flowchart showing an on-operation process periodically executed by the microcomputer 10 (specifically, executed by the CPU 12) when the microcomputer 10 is operating.

  In this operation processing, first, in S110, it is determined whether or not a predetermined operation stop condition is satisfied. For example, when it is determined that the IGSW 2 is turned off and a predetermined process such as a communication process is completed, it is determined that the operation stop condition is satisfied.

If it is determined in S110 that the operation stop condition is not satisfied (S110: NO), the process is terminated as it is.
On the other hand, if it is determined in S110 that the operation stop condition is satisfied (S110: YES), the process proceeds to S120, and it is determined whether or not the authentication process for authenticating with the smart portable device is completed. In other words, it is determined whether the switching condition is satisfied.

If it is determined in S120 that the authentication process has not ended (S120: NO), the process of S120 is repeated again.
On the other hand, if it is determined in S120 that the authentication process has been completed (S120: YES), whether or not the interval from the signal to the next cycle of the signal (pulse) from the PWM circuit 20 is equal to or longer than a predetermined time. Determine whether. Specifically, based on the count value of the counter incorporated in the PWM circuit 20, the interval until the next cycle of the signal is calculated, and it is determined whether or not the calculated interval is equal to or longer than a predetermined time (predetermined interval). To do.

  If it is determined in S130 that the interval until the next cycle is equal to or longer than the predetermined time (S130: YES), the process proceeds to S140, and the timer value in the timer circuit 22 is set. As described above, the timer circuit 22 measures the time, and when the time indicated by the timer value arrives, the timer circuit 22 outputs a start signal to start the microcomputer 10.

  Next, it progresses to S150 and the process for transfering to a sleep mode is performed. Specifically, the operation of the main oscillation circuit 28 is stopped and the operation clock is switched to the sub clock from the sub oscillation circuit 26. That is, it shifts to the sleep mode.

  On the other hand, if it is determined in S130 that the interval until the next cycle is not equal to or longer than the predetermined time (S130: NO), the process proceeds to S160 and the switching process is executed. The switching process is a process of switching authentication with the smart portable device from normal authentication executed by the microcomputer 10 to simple authentication executed by the communication IC 40. Specifically, it is a process of setting a duty ratio for a pulse output from the PWM circuit 20 (that is, a process of outputting a pulse having a predetermined duty ratio from the PWM circuit 20). After S160, the process proceeds to S150.

Next, FIG. 3 is a flowchart showing a startup process that the microcomputer 10 executes immediately after startup (specifically, executed by the CPU 12).
In this startup process, first, in S210, it is determined whether or not to execute a normal process when the IGSW 2 is turned on and started up. For example, the determination is based on whether or not the current activation is associated with the IGSW 2 being turned on. Note that the logic level of the signal S can be read from the IGSW 2 to determine whether the IGSW 2 is turned on.

If it is determined in S210 that the normal process is to be executed (S210: YES), the process proceeds to S220 and the normal process is executed. Thereafter, the process proceeds to S230.
If it is determined in S210 that the normal process is not executed (S210: NO), the process proceeds to S230.

  In S230, it is determined whether or not to execute the switching process. Specifically, the determination is based on whether or not the current activation is due to an activation signal from the timer circuit 22. If it is determined that the current activation is due to the activation signal from the timer circuit 22, it is determined that the switching process is to be executed (S230: YES), and the process proceeds to S240 to execute the switching process. Thereafter, the process proceeds to S250.

Moreover, if it determines with not performing a switching process in S230 (S230: NO), it will transfer to S250.
In S250, it is determined whether to execute the authentication process. Specifically, the determination is based on whether or not the current activation is based on a signal from the communication IC 40 (response signal from a smart portable device not shown). If it is determined that the current activation is due to a signal from the communication IC 40, it is determined that the authentication process is to be executed (S250: YES), and the process proceeds to S260 to execute the authentication process. Thereafter, the process proceeds to S270.

If it is determined in S250 that the authentication process is not executed (S250: NO), the process proceeds to S270.
In S270, it is determined whether or not to shift to the sleep mode. For example, when a process to be executed at the time of startup is executed and it is determined that there is no other process to be executed, it is determined to shift to the sleep mode (S270: YES), and the process shifts to S280 to execute the sleep mode shift process. That is, it shifts to the sleep mode.

On the other hand, if it is determined in S270 that the mode does not shift to the sleep mode (S270: NO), the process is terminated as it is.
Next, FIG. 4 is a flowchart showing processing realized in the timer circuit 22.

  In the timer circuit 22, first, it is determined whether or not the timer value measured by itself has reached the set value preset by the CPU 12, and if it is determined that the timer value has not reached the set value (S310). : NO), the process of S310 is executed again.

On the other hand, if it is determined in S310 that the timer value has reached the set value (S310: YES), an activation signal is output in S320. This is the end of the process.
Next, FIGS. 5 and 6 are time charts showing the operation of the present embodiment.

  5 and 6 (a) and 6 (b), the first level represents the operation state (wake or sleep) of the microcomputer 10, and the second level represents the drive timing of the communication IC 40 (in other words, the simple authentication timing by the communication IC 40). The third row represents the authentication timing by the microcomputer 10.

First, a description will be given with reference to FIG.
In the ECU 1 of the present embodiment, as shown in the first stage, the microcomputer 10 sets the duty ratio to a predetermined value when the switching condition is satisfied (the operation stop condition is satisfied and the authentication process is completed) (time t1). The setting process is executed (time t2 to t3) so that a pulse is output from the PWM circuit 20, and then the mode is shifted to the sleep mode.

  As shown in the third row, the microcomputer 10 periodically performs an authentication process until the switching condition is satisfied. Specifically, a transmission request signal is periodically transmitted to the surroundings via the communication IC 40. Then, if a response signal from the smart portable device that has received the transmission request signal can be received, whether or not the ID code included in the received response signal matches the ID code registered in advance in the microcomputer 10 is verified. (Period L1).

  Here, in the present embodiment, as shown in the first and second stages, when the switching condition is satisfied, the microcomputer 10 until the switching period is satisfied and immediately before the next cycle (time t1 to t2). Once in sleep mode, it starts up just before the next cycle. And the process which sets the above-mentioned duty ratio to a predetermined value is performed.

  This is for the following reason. Specifically, even if the duty ratio is set in the current period when the condition is satisfied, the set value is reflected (that is, the pulse with the set duty ratio is output) after the next period. This is because. That is, it is sufficient to set the duty ratio just before the next cycle.

  The communication IC 40 is driven according to the pulse from the PWM circuit 20, transmits a transmission request signal to the surroundings, and performs simple authentication as to whether or not a response signal from the smart portable device has been received ( Period L2). Here, while the microcomputer 10 is activated, the pulse from the PWM circuit 20 is not output. This is realized by setting the pulse duty ratio to 0 while the microcomputer 10 is in the wake mode.

  As described above, in this embodiment, when the microcomputer 10 sets the duty ratio and shifts to the sleep mode because the switching condition is satisfied, the microcomputer 10 temporarily shifts to the sleep mode until immediately before the next cycle. Yes. For this reason, the power consumption of the microcomputer 10 is reduced.

Next, the effect | action of this embodiment is demonstrated in detail using FIG.
Here, in FIGS. 6A and 6B, the fourth stage shows the change in the count value of the counter built in the PWM circuit 20.

  As shown in the fourth stage of FIGS. 6A and 6B, the counter of the PWM circuit 20 counts from 0 to S. When the count value reaches S, the count value is reset to zero. The period during which the counter counts from 0 to S coincides with the period representing the pulse period. That is, the counter keeps a time period representing the cycle.

  6A, when the operation stop condition is satisfied (time t4, S110: YES) and the authentication process is completed (time t5, S120: YES), the microcomputer 10 sets the count value of the counter of the PWM circuit 20 to the count value. Based on this, the interval from the present to the next cycle is calculated (S130), and if the interval is longer than the predetermined time (S130: YES), the mode is temporarily shifted to the sleep mode (time t5, S150). At this time (before shifting to the sleep mode), the timer circuit 22 is notified of the time until immediately before the next cycle (S140). Here, the time until the next cycle is the following time. Specifically, from the time from the present to the next cycle, the time required for start-up (time required from start-up to transition to normal operation) and time required for switching processing (duty ratio setting) are combined. This is the subtracted time (t5 to t6).

  The timer circuit 22 measures time (period), and outputs a start signal when the notified time (period) arrives (S310: YES). Thereby, the microcomputer 10 is activated (time t6).

  When the microcomputer 10 is activated, it is determined that the microcomputer 10 has been activated by the activation signal from the timer circuit 22 (S230: YES), and the switching process is executed (S240). When the switching process is completed at time t7 (when a pulse is output from the PWM circuit 20), the process shifts to the sleep mode (S280).

After the microcomputer 10 shifts to the sleep mode at time t7, the communication IC 40 is periodically driven according to the pulse from the PWM circuit 20 to execute simple authentication.
Next, as shown in FIG. 6B, when the switching condition is satisfied (time t8, S110, S120: YES), the interval from the present to the next cycle is determined based on the count value of the counter of the PWM circuit 20. If it is shorter than the predetermined time (S130: NO), the switching process is executed without shifting to the sleep mode (S160). This ensures that a pulse is output from the next cycle when the switching condition is satisfied.

  As described above, in the present embodiment, the period during which the state of the microcomputer 10 is in the sleep mode is maintained while ensuring that the authentication by the microcomputer 10 is switched to the simple authentication by the communication IC 40 (while maintaining the performance of the ECU 1). More power can be secured, and the power consumption of the microcomputer 10 and thus the ECU 1 can be further reduced.

  In the above-described embodiment, the communication IC 40 and the transmission antenna 60 correspond to a transmission unit, the communication IC 40 and the reception antenna 50 correspond to a reception unit, the process of S260 corresponds to an authentication unit, and the communication IC 40 also includes a communication circuit. The PWM circuit 20 corresponds to a pulse output circuit.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various form can be taken within the technical scope of this invention.
For example, in the above embodiment, the communication IC 40 may be driven at the falling edge of the pulse from the PWM circuit 20.

  Further, in the above embodiment, when the switching condition is satisfied, the microcomputer 10 executes the switching process and then temporarily shifts to the sleep mode until immediately before the next cycle, and starts immediately before the next cycle, It may be configured to confirm that the switching process has been completed (that is, that a pulse has been output from the PWM circuit 20), and shift to the sleep mode again.

  Further, in the above embodiment, when the switching condition is satisfied, if the interval from the present to the next cycle is shorter than the time required for the switching process, the microcomputer 10 does not meet the next cycle even if the switching process is executed. May temporarily shift to the sleep mode until immediately before the next cycle, and may be activated immediately before the next cycle.

  Further, in the above embodiment, in the timer circuit 22, when the timer value counted by the timer circuit 22 becomes a preset value set by the CPU 12, the timer circuit 22 outputs a start signal so that the microcomputer 10 is started. However, in the sleep mode, the CPU 12 monitors the timer value of the timer circuit 22, and when the timer value reaches a preset setting value, the CPU 12 operates the main oscillation circuit 28 and operates. The clock may be switched to the main clock from the main oscillation circuit 28 (that is, the microcomputer 10 is activated).

It is a block diagram showing schematic structure of ECU1 of this embodiment. It is a flowchart showing the process at the time of operation performed in the microcomputer 10 of ECU1. It is a flowchart showing the process at the time of starting performed in the microcomputer 10 of ECU1. 3 is a flowchart showing processing realized in a timer circuit 22. It is a time chart showing the effect | action of this embodiment (the 1). It is a time chart showing the effect | action of this embodiment (the 2). It is a time chart showing the conventional authentication control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic control unit (ECU), 2 ... Ignition switch (IGSW), 10 ... Microcomputer, 12 ... CPU, 14 ... ROM, 16 ... RAM, 18 ... Counter, 20 ... PWM circuit, 22 ... Timer circuit, 24 ... On Output port, 26 ... sub oscillation circuit, 28 ... main oscillation circuit, 30 ... power supply IC, 40 ... communication IC, 50 ... receiving antenna, 60 ... transmitting antenna, 100 ... electronic control unit (ECU), 110 ... microcomputer, 120 ... Communication circuit, 130 ... reception antenna, 140 ... transmission antenna.

Claims (5)

A transmission means for transmitting a transmission request signal to the surroundings;
Receiving means for receiving a return signal transmitted in response to the transmission request signal from a portable device possessed by the user;
Authentication means for performing authentication by determining whether or not the identification information included in the received return signal is pre-registered identification information, and specific vehicle control if the authentication by the authentication means is successful A microcomputer that is configured to stop the operation when a predetermined operation stop condition is satisfied,
While the operation of the microcomputer is stopped, it is driven for a predetermined period at the rising or falling timing of the input signal, and instead of the microcomputer, the transmission request signal is transmitted while the return signal is received and the return that has been received. A communication circuit for outputting a signal to the microcomputer,
The microcomputer further includes:
It has a pulse output circuit that outputs a pulse to the communication circuit, and when the operation stop condition is satisfied, the pulse is output to the pulse output circuit by setting the duty ratio of the pulse before stopping its own operation In the in-vehicle device for smart entry system that is configured to stop its own operation after confirming the normal operation of the pulse output circuit,
When the operation stop condition is satisfied, the microcomputer temporarily stops its operation until immediately before the next cycle of the pulse (hereinafter referred to as the next cycle), and starts up immediately before the next cycle to start the duty ratio. And the operation of the pulse output circuit is confirmed in the next cycle. The in-vehicle device for a smart entry system according to claim 1,
The microcomputer determines that the operation may be stopped when the authentication by the authentication unit is completed in addition to the operation stop condition being satisfied, and temporarily stops the operation until immediately before the next cycle. An in-vehicle device for a smart entry system, characterized in that In the in-vehicle device for a smart entry system according to claim 1 or 2,
When the operation stop condition is satisfied, if the interval until the next cycle is shorter than a predetermined time, the microcomputer exceptionally does not stop its operation until the next cycle, and the next cycle An in-vehicle apparatus for a smart entry system, wherein the duty ratio is set before the arrival of, and the operation of the pulse output circuit is confirmed in the next cycle. The in-vehicle device for a smart entry system according to claim 3,
The in-vehicle device for a smart entry system, wherein the predetermined time is at least the time required for starting the microcomputer and the time required for setting the duty ratio. In the in-vehicle device for smart entry system according to claim 3 or claim 4,
The microcomputer includes a counter that measures a period representing the cycle, and based on a count value of the counter, recognizes an interval from when the operation stop condition is satisfied to the next cycle. In-vehicle device for smart entry system.

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